Madelyn Gillentine, who suggests around 25 per cent of those with mutations in the HNRNPU gene have autism

The team collected genetic data from more than 11,000 people with neurodevelopmental conditions. Eleven of these have mutated HNRNPU genes.

Genetic mutations and autism

The University of Washington team is also investigating how the genetic mutations can be a factor in causing autism.

Gillentine believes the rate of autism in those with mutated HNRNPU genes is “about 25 per cent”.

But she believes the “proportion could change over time” as more people are seen with the condition.

Physical problems

Last year, research led by Nuria Bramswig at the University of Duisburg-Essen, in Germany, linked variants of HNRNPU to a range of physical problems.

These included low muscle tone and heart, kidney and central nervous system problems.

Other research has linked the variants of HNRNPU to additional problems. These include microcephaly, or an abnormally small head, and the partial or complete absence of a part of the brain that connects two hemispheres.